Voice over IP (VoIP) systems are being used to, among other things, replace conventional PBX's in offices. Wireless fidelity (Wi-Fi) systems, which transmit IP data, are being deployed in office buildings and on campuses to obviate the need for a wired LAN connection for computers and other equipment that is networked, and to provide wireless telephone service (wireless VoIP) as an alternative to conventional cellular systems such as TDMA, CDMA, GSM, and 3G. At present the conventional cellular systems' coverage area is much greater than the total area covered by wireless VoIP systems for several reasons, a main reason being the relative newness of the wireless VoIP system. However, there are other problems deploying wireless VoIP systems such as battery capacity and tolerance to RF disturbances. On the other hand, Wi-Fi systems, because they transmit IP data directly between the individual computer or similar equipment (the client) and an access point (AP) provide significantly higher data rates than conventional cellular systems available today or will be available in the near future.
Mobile wireless VoIP telephones require more intensive data processing than conventional cellular telephones and therefore require more battery power and consequently more frequent battery charging or larger capacity (and heavier) batteries than conventional cellular telephones. A method to reduce the battery drain is to reduce the RF transmission signal level from the telephone. This results in smaller areas of coverage for each access point (AP)/base station than for each base station in a conventional cellular system, and consequently more base stations are required than conventional cellular base stations for a particular area. Therefore, the cost of purchasing and installing each base station is more of a critical factor in wireless VoIP systems.
While the conventional cellular systems were initially designed for roaming from one cell to another without a disturbance in the voice communication, the Wi-Fi system was initially designed for electronic equipment which can tolerate gaps in the data flow to the equipment. The most common protocol for wireless IP communication is the IEEE 802.11 standard. This standard requires termination of a first connection between a user and an AP before connection to the new AP, then reauthentication usually including encryption coordination and establishment of a new connection. This process produces gaps in the voice transmission which are noticeable to a Wi-Fi telephone user.
Therefore, it can be appreciated that a Wi-Fi system for mobile users over a wide area such as a metropolitan area that is relatively inexpensive to build, and that provides virtually uninterrupted voice transmission when a mobile telephone user is changing connections from one AP to another is highly desirable.
It is an object of the present invention to provide an AP configuration that is relatively inexpensive to build and install.
It is a further object of the invention to provide a Wi-Fi system that does not create disturbances for mobile telephone user.
It is a still further object of the invention to provide a Wi-Fi system that can be used for both voice and computer data without degrading the voice communications and that is not significantly more expensive than a voice only system.